Proximal humerus fractures, although common, have high rates of failure after open reduction and internal fixation. The use of a fibular allograft has been explored as a means to decrease complications, particularly varus collapse and the need for revision surgery. The authors performed a retrospective review of 133 proximal humerus fractures managed surgically with locking plates (n=72) or locking plates with fibular allograft intramedullary struts (n=61). Demographic, intraoperative, and postoperative variables were collected and analyzed. The fibular allograft group was more likely to be older (P<.01), be female (P=.04), and have a history of osteoporosis (P=.01). No differences were noted in the proportions of 2-, 3-, or 4-part fractures between groups. Average follow-up was 28 weeks. Medial calcar length was longer in the locking plate only group (P=.04); however, this group demonstrated a decreased head shaft angle (P=.01) and a trend toward increased rates of varus collapse (P=.06). No significant differences were found regarding other radiographic complications, irrespective of fracture complexity. A notable decrease in fluoroscopy time was seen with strut use (P=.04), but operative time and blood loss were similar between groups. A significant decrease in revision surgery rate was found with use of an allograft strut (P=.05). Using a strut appears to preserve the radiographic head shaft angle and decrease the risk of fracture collapse in 2-, 3-, and 4-part fractures, without increasing surgical time or morbidity. Use of an intramedullary strut appears to reduce the need for revision surgery, particularly in 3- and 4-part fractures. [Orthopedics. 2020;43(5):262-268.].